Volume 9 Issue 6, June 2007

Exciting new work identifies phospholipase D2 (PLD2) as an unexpected player upstream of Ras activation in epidermal growth factor (EGF)- and T-cell receptor-regulated signalling pathways. Phosphatidic acid (PA) generated on the plasma membrane by activated PLD2 directly recruits the guanine nucleotide-exchange factor Sos, or after conversion to diacylglycerol (DAG), recruits RasGRP1. These results demand a rewiring of some well-established circuit diagrams.

Small open-reading frames are difficult to detect both computationally and by mutagenesis. An mRNA previously thought to be non-coding has now been found to produce four tiny peptides that function non-cell autonomously to organize epithelial actin during Drosophila development.

In the cell, microtubule organizing centers (MTOCs) dynamically nucleate microtubules and arrange them in functional patterns, but microtubule anchoring to MTOCs is not well understood. A novel fission-yeast protein that anchors the γ-tubulin-containing nucleating complex (γ-TuC) at the spindle pole during mitosis has now been described. The work highlights the complex regulation of microtubule anchoring.

Caspases are proteases that regulate apoptosis as well as inflammation. Denecker et al. show that caspase-14 controls the maturation of the epidermis by proteolytically processing filaggrin. The ultimate products of this cleavage prevent UVB photodamage and water loss, affecting skin osmolarity and moisture. Although this work sets caspase-14 apart from its family members, it also reinforces their role in host defence responses.